The McLeod Syndrome is a clinical entity with x-linked inheritance which involves erythropoietic, neurologic and muscular tissues. The propositus of this syndrome lives in Albuquerque and has been followed at the University of New Mexico School of Medicine and Lovelace Medical Center. Neuromuscular changes have been noted in this phenotype but not previously extensively characterized. The purpose of this project is to extensively characterize the neuromuscular defect in this syndrome.